| Parameter | Type | Default | Description |
|-----------|------|---------|-------------|
| `event` | `str` | `WorkflowRunEvent.workflow_cancelled.value` | Event type identifier |
| `reason` | `Optional[str]` | `None` | Reason for workflow cancellation |
| `is_cancelled` | `bool` | `True` | Property indicating the workflow was cancelled |
| *Inherits all fields from `BaseWorkflowRunOutputEvent`* |